Comparing to Default model (the green shaded region) used in [1]}, we observe substantially more uncertainty in the inferred spin magnitude distributions using our spline models. By construction, the Default model requires \(p(a = 0) = 0\) , but this is ruled out from the spline model at the 90% level.
As a point of comparison, in Appendix  we show the distribution of spin magnitudes for different numbers of nodes, this time assuming 4 nodes in the tilt distribution. We find no significant differences from the distributions assuming 10 nodes in the tilt distribution which indicates that the number of nodes in the tilt distribution has a negligible effect on the inferred spin magnitude distribution.
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